Interiorization is the process of development of main social mechanisms of man's consciousness. However the nowadays psychology can not tell us how it is actually going on in ontogenesis. Specificity of the process consists in the fact that social mechanisms of consciousness (and the very function of signification in particular) take shape in the process of interaction, communication, dialogue between an infant, with his not yet fully developed consciousness, and an adult (adults). Interiorization becomes a specific (and initial for all subsequent) type of communication. What makes it so specific is that the infant with his too-far-from-mature mind is somehow capable to acquire the very structure of dialogical relations. This structure becomes so far the generative, nuclear for the function of signification, for all conscious psychological processes.